Starter quiz
- Which of the following particles are found in the nucleus of an atom?
- electrons
- protons ✓
- neutrons ✓
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- An isotope can be defined as …
- an atom of the same element with a different number of neutrons. ✓
- an atom of a different element with the same number of neutrons.
- an atom of the same element with a different number of protons.
- an atom with the same atomic number but different mass number. ✓
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- What are the possible differences between substances that contain isotopes of the same element?
- they have different masses ✓
- they have different chemical reactivities
- some isotopes are more stable than others ✓
- there are no differences
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- Which particle affects the stability of a nucleus, and what factors determine if a nucleus is stable or unstable?
- protons affect the stability of a nucleus
- neutrons affect the stability of a nucleus ✓
- a nucleus is stable with more protons than neutrons
- a nucleus is stable when the neutron–to–proton ratio is balanced ✓
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- Which of these can be released during nuclear reactions such as nuclear decay?
- alpha particles ✓
- beta particles ✓
- neutrons ✓
- light
- energy ✓
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- Which of the following statements accurately describes the changes that occur in the nucleus during radioactive decay?
- Decay always emits gamma rays with no change in the nucleus.
- Decay can emit alpha/beta particles or gamma rays, changing atomic no/mass no. ✓
- Decay only emits particles, with no nucleus changes or energy release.
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Exit quiz
- What is nuclear fission?
- Breaking down electrons into protons and neutrons.
- Splitting a heavy nucleus into smaller nuclei, releasing energy. ✓
- Emitting radiation from a substance without changing the nucleus.
- Combining two light nuclei to form a heavier nucleus.
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Which of the following nuclear equations could represent the fission of a uranium–235 nucleus?- Equation 1 ✓
- Equation 2 ✓
- Equation 3
- Equation 4
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- Put the following stages of fission in the correct order, starting with a uranium–235 nucleus (U–235) absorbing a neutron.
- 1⇔A U–235 nucleus absorbs a neutron, becoming a U–236 nucleus.
- 2⇔The U–236 nucleus is unstable and splits into two, smaller nuclei.
- 3⇔As well as the smaller nuclei, 2 or 3 neutrons are released.
- 4⇔Energy, in the form of gamma radiation, is also released.
- 5⇔More U-235 atoms absorb the released neutrons.
- 6⇔A chain reaction occurs when more U–235 nuclei split releasing more neutrons.
- What is the key difference between spontaneous fission and induced fission?
- Spontaneous fission needs external triggers; induced happens by itself.
- Induced fission occurs naturally; spontaneous requires a neutron to be absorbed.
- Spontaneous fission occurs naturally; induced requires a neutron to be absorbed. ✓
- Both types of fission occur due to temperature changes and external triggers.
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- What is nuclear fusion?
- Breaking down electrons into protons and neutrons.
- Splitting a heavy nucleus into smaller nuclei, releasing energy.
- Emitting radiation from a substance without changing the nucleus.
- Combining two light nuclei to form a heavier nucleus. ✓
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- Nuclear fusion powers stars by combining light nuclei, such as hydrogen, into heavier elements. Why isn’t nuclear fusion currently a viable method for generating electricity on Earth?
- It is too dangerous, producing large amounts of harmful radiation.
- It only works with special fuels not found on Earth.
- It requires extremely high temperatures and pressure, hard to recreate on Earth. ✓
- It generates less energy than nuclear fission.
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Worksheet
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Presentation
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Lesson Details
Key learning points
- Nuclear fission is the splitting of a large and unstable nucleus such as uranium or plutonium.
- A neutron fired at a uranium nucleus can cause nuclear fission that splits the nucleus and emits 2 or 3 more neutrons.
- The motion of all the particles shot out from a nuclear fission can cause heating by making other particles move faster.
- Neutrons shot out from a nuclear fission can split more uranium nuclei in a chain reaction.
- Nuclear fusion is the joining of two light nuclei to form a heavier nucleus with the creation of gamma radiation.
Common misconception
Radioactive isotopes disappear when they decay, so that in one half-life half the mass is lost.
Emphasise that the mass of the nuclei at the end of a nuclear fission or fusion are almost identical to the masses of those at the start. There is a very small difference, with mass being converted to energy according to E = mc².
Keywords
Nuclear fission - the splitting of large nuclei to form pairs of smaller nuclei and some free neutrons, with the release of energy
Daughter nuclei - the smaller nuclei produced during nuclear fission
Chain reaction - a series of nuclear fission events, with each one triggered by a neutron from a previous nuclear fission
Nuclear fusion - the combining of small nuclei at very high temperatures with the release of energy
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